Silicone rubber products are used in various high temperature environments due to their excellent heat resistance. In recent years, silicone rubber products are used in microwave ovens, inside of heating furnaces, engine compartments of automobiles, and the like, in which a high heat resistance in higher temperature environments, such as in a temperature exceeding 200° C. for example, is required. In light of such circumstances, to further enhance the heat resistance of silicone rubber, it has been widely known to compound a small quantity of titanium oxide, cerium oxide, cerium hydroxide, or carbon black as a heat resisting material.
For example, Japanese Unexamined Patent Application Publication No. H11-158382A describes a silicone rubber composition, containing anatase type titanium oxide fine powder, used as a sealing/packing material for various food containers that are required to have high heat resistance.
Furthermore, Japanese Unexamined Patent Application Publication No. 2003-331653A describes a silicone rubber composition containing a solid solution of iron oxide and titanium oxide. However, this silicone rubber composition is for a rubber stress cone used in cables. Therefore, only the fact that the silicone rubber composition is characterized by having good weatherability is expressly mentioned, and this silicone rubber composition is not designated for applications that require high heat resistance. Furthermore, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. H09-502299A also describes a silicone rubber composition containing iron oxide and titanium oxide; however, this composition is also for the purpose of using as an insulator, only the fact that the composition has a high flashover resistance and arc-resistance is expressly mentioned, and this composition is also not designated for applications that require high heat resistance.